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Arguably one of the most significant contributions to health care made by the osteopathic medical profession is the development of the concept of viscerosomatic and somatovisceral interactions.1 Initially published by Burns in 19072 and later researched by Korr,3 the concepts of viscerosomatic reflexes and facilitated segments are now regularly taught in osteopathic medical schools. However, the concepts are in great need of further research to establish clinical significance and applications in medical treatment. Likewise, the use of visceral manipulation4 is also in need of more empirical examination. This study was selected for review because it pertains to both osteopathic theory and practice.

Researchers at the British College of Osteopathic Medicine and Swansea University in the United Kingdom evaluated the effect of visceral manipulation therapy (VMT) on pressure pain thresholds in 15 healthy, asymptomatic participants in this single-blinded, randomized, within-subjects, repeated measures study. The experimental procedure comprised 1 minute of VMT to the sigmoid colon in the left iliac fossa, drawing it superolaterally, and then releasing it. This procedure was repeated at a frequency and amplitude determined by the tissue response, as is typical in clinical practice. The sham intervention was 1 minute of light manual contact over the umbilical region with no treatment intention or tissue barrier engagement. When receiving VMT and sham therapy, participants were told they were receiving osteopathic therapy. The control session consisted of the researcher simply being present for 1 minute. All interventions were carried out by a registered osteopath with clinical experience using VMT. All participants received each intervention with a minimum of 48 hours between sessions.

The dependent variable was pressure pain threshold (PPT) as measured by a handheld manual pressure algometer. One algometer reading was made at the L1 level, 1 cm left-lateral to the spinous process. This site was chosen for its established segmental level for autonomic innervation associated with the sigmoid colon. The first dorsal interossei on the right hand was used to monitor any systemic response to the interventions. Readings of PPT were made immediately before and after the interventions. Participants were instructed to report when the pressure applied by the algometer transitioned from an experience of pressure to a painful sensation.

The results showed a statistically significant difference for pre- and postintervention PPTs in the lumbar spine (P<.0001) with no differences reported for the sham or control groups. The mean change for lumbar spine PPT readings was 18.4%, which was above the literature-established level of 15% as indicative of clinically meaningful change.

Limitations of the study are that it used a small sample and did not use a participant-activated button press for reporting pain, which means that there could have been a pain perception report from a time-delayed verbal report that the PPT assessor visually measures. Also, the use of asymptomatic participants raised questions as to whether the effects would have been less if participants with visceral or musculoskeletal disorders were used. Also lacking is any assessment of the duration of effect.

Although it appears that a viable and likely mechanism of action in this study was a neurophysiological process related to the concept of viscerosomatic reflexes, the design is not robust enough to justify anything more than the usual statement that more research is needed before any definitive conclusion can be made. However, the authors should be acknowledged for presenting a novel research design to explore both the application of VMT and the osteopathic concept of viscerosomatic interactions.

“The Somatic Connection” highlights and summarizes important contributions to the growing body of literature on the musculoskeletal system's role in health and disease. This section of The Journal of the American Osteopathic Association (JAOA) strives to chronicle the significant increase in published research on manipulative methods and treatments in the United States and the renewed interest in manual medicine internationally, especially in Europe.